A stereoscopic camera, which can simultaneously obtain a left-eye image and a right-eye image from an object using two cameras, generally includes a left-eye camera for obtaining a left-eye image from an object, a right-eye camera for obtaining a right-eye image from an object, and a stereoscopic camera rig for supporting the left-eye camera and the right-eye camera.
The stereoscopic camera rig is largely classified into a parallel type (horizontal type) and a perpendicular type. The parallel type of stereoscopic camera rig supports left-eye camera and a right-eye camera in parallel with each other toward an object such that the left-eye camera and the right-eye camera individually acquire images by receiving light from the object.
According to the perpendicular type of stereoscopic camera rig, as shown in FIG. 1, left-eye and right-eye cameras 4 and 2 are arranged perpendicularly to each other, in which the right-eye camera 2 is disposed on the axis of light reflected from a half mirror H and the left-eye camera 4 is disposed on the axis of light passing through the half mirror H so that the left-eye camera 4 and the right-eye camera 2 can acquire images 3 and 5 by indirectly receiving light from an object 1 through the half mirror H.
In particular, a perpendicular type of stereoscopic camera can be reduced in volume in a plane, as compared with a parallel type of stereoscopic camera, so it is very useful for shooting when a large movement radius of the camera is required, for example, when the camera is mounted on a jimmy jib.
The perpendicular type of stereoscopic camera rig has to be able to strongly fix the cameras 2 and 4 and needs to precisely adjust the position and the angle of the cameras 2 and 4 to adjust the convergence angle and the binocular disparity ‘d’ between images 3 and 5 acquired by the left-eye camera 4 and the right-eye camera 4; however, the cameras are frequently moved for photographic effect, so it is difficult to adjust the position and the angle of the cameras 2 and 4 during shooting.
A plan for solving this problem has been disclosed in Korean Patent No. 1214855 (titled, “Stereo camera rig having harf-mirror box).
The stereo camera rig holds any one or both of a left-eye camera 4 and a right-eye camera 2 in an adjustment module and adjusts the binocular disparity using the adjustment module. That is, the adjustment module performs both of a function of adjusting the binocular disparity ‘d’ by straightly moving the cameras therein and a function of adjusting the convergence angle by turning the cameras.
However, it is complicated to adjust the binocular disparity and convergence angle using the adjustment module, so it is difficult to use the adjustment module at an actual shooting site. Further, there is another problem that the structure of the adjustment module is very complicated, so manufacturing is difficult and the manufacturing cost is high.
On the other hand, a first image formation lens 6 may be disposed ahead of the half mirror H in the stereoscopic camera rig. The first image formation lens 6 concentrates light from an object 1 and the first image formation lens 6 should be appropriately selected, depending on the type of the object 1, the distance to the object 2, and the shooting purpose, but the available type of the first image formation lens 6 is limited by the size and position of imaging plates of the cameras 2 and 4, and lenses. Accordingly, it is required to improve the configuration of stereoscopic cameras in order to more extensively select and use the first image formation lens 6 that is the most suitable for shooting.